The present invention relates to a wet scanning gate and its use in the production of enlargements of individual photographic negatives or transparencies (slides). A wet scanning gate of this type is disclosed in the unpublished German Patent Application P 40 32 016.2.
U.S. Pat. No. 3,776,626 discloses a wet copying device, which, like the above noted prior art wet scanning gate, serves to wet the top and bottom surfaces of the film material during passage of surface damaged film material through the gate of the film copying machine or film scanner with a liquid which has the same optical refractive index as the film material. This liquid completely fills the scrapes and scratches present on the film surface so that they are no longer included in film copy or electronic image signal. These devices, which are configured as closed systems, include a chamber equipped with extraction zones upstream and downstream of the optical gate as well as a drying zone following the downstream extraction zone to prevent escape of the perchloroethylene, employed as the liquid, into the environment. The liquid is injected immediately upstream and downstream of the optical gate onto the top and bottom surfaces of the film material in a direction oblique to the film surface.
For the production of paper enlargements of individual photographic negatives it is likewise desirable to make damages to the negative surface invisible. Although prior art enlargers (see in-house brochure by Agfa-Gevaert entitled "Multi Scanning Printer") are configured similarly to film copying machines, that is, the photographic negatives are assembled into a coiled strip and are pulled in steps or continuously in parallel with a strip of photographic paper through the beam path of a light source and enlarging lenses, the wet copying technique that has been known for several decades has not been employed in enlargers. Existing differences between the film drives which employ film gripping pins or friction rollers and the drives for the coiled strip in the form of friction rollers cannot be considered as the reason for the lack of use of the wet copying process at least not for the wet scanning process, since the film scanners employed for wet scanning also drive the film by means of a friction roller. The more probable explanation for the lack of use of wet copying and wet scanning in enlargers is that the gluing together of photonegatives into a strip does not produce a strip that is comparable to a film. That is, while a film has a completely smooth surface, a glued-together strip of negatives is more or less heavily corrugated. Thus, when pulled through the prior art wet copiers or wet scanning devices, the glued-together strip of negatives is subjected to relatively high friction forces and thus high tensile stresses because of the small thickness of the transporting channel existing there, which may result in a tearing apart of the glued sections between the individual negatives.